# How to find the average of a particular column in R data frame?

R ProgrammingServer Side ProgrammingProgramming

To find the average of a particular column in R data frame, we can take the help of delta ($) operator. For example, if we have a data frame called df that contains a column x then we can find the average of column x by using the command given below − mean(df$x)

## Example 1

Following snippet creates a sample data frame −

x1<-rnorm(20)
x2<-rnorm(20)
x3<-rnorm(20)
df1<-data.frame(x1,x2,x3)
df1

The following dataframe is created −

       x1           x2           x3
1   0.08296609  -0.98030681  -0.37284625
2  -0.77756287  -2.00417903   0.99687606
3   0.72853715   0.01054841   0.21984261
4   0.32172853  -0.15294023   0.81413538
5   0.14037370  -1.72069152  -0.40727802
6  -0.46377087  -0.44384035  -0.27233178
7  -0.07626076  -0.55753570   0.09087911
8  -0.15585465   1.02326012   0.59296301
9   0.36429494   0.48666242  -0.29251297
10 -1.71607624  -1.14980411  -0.52830887
11 -0.13649599  -0.48478367   0.57505756
12  0.20013689  -1.07749624   1.78867277
13 -0.78971636  -1.35245763   0.03213526
14 -1.08909636  -0.58043334  -0.32440015
15 -0.16291871   0.08974447   0.64379662
16 -0.16230288  -0.27600414   0.09700218
17 -0.71638476   0.36130502   1.63317291
18  0.22151476   0.95380907  -0.12504823
19 -1.72743039  -1.01398759   1.05922322
20  0.11511031   0.09696002   0.90670155

To find the mean of column x1, add the following code to the above snippet −

x1<-rnorm(20)
x2<-rnorm(20)
x3<-rnorm(20)
df1<-data.frame(x1,x2,x3)
mean(df1$x1) If you execute all the above given snippets as a single program, it generates the following output −  -0.2899604  To find the mean of column x2, add the following code to the above snippet − x1<-rnorm(20) x2<-rnorm(20) x3<-rnorm(20) df1<-data.frame(x1,x2,x3) mean(df1$x2)

If you execute all the above given snippets as a single program, it generates the following output −

 -0.4386085


To find the mean of column x3, add the following code to the above snippet −

x1<-rnorm(20)
x2<-rnorm(20)
x3<-rnorm(20)
df1<-data.frame(x1,x2,x3)
mean(df1$x3) If you execute all the above given snippets as a single program, it generates the following output −  0.3563866  ## Example 2 Following snippet creates a sample data frame − y1<-rpois(20,2) y2<-rpois(20,5) y3<-rpois(20,1) y4<-rpois(20,5) df2<-data.frame(y1,y2,y3,y4) df2 The following dataframe is created −  y1 y2 y3 y4 1 0 3 2 2 2 4 3 1 4 3 0 6 1 9 4 2 2 0 5 5 2 3 0 5 6 2 6 2 6 7 0 4 0 3 8 2 7 0 1 9 3 5 2 2 10 3 4 1 4 11 0 6 2 3 12 1 4 1 4 13 3 4 0 7 14 1 2 2 10 15 2 4 0 5 16 4 4 2 4 17 1 3 0 5 18 0 4 3 7 19 2 4 1 6 20 2 3 0 6 To find the mean of column y1, add the following code to the above snippet − y1<-rpois(20,2) y2<-rpois(20,5) y3<-rpois(20,1) y4<-rpois(20,5) df2<-data.frame(y1,y2,y3,y4) mean(df2$y1)

If you execute all the above given snippets as a single program, it generates the following output −

 1.7


To find the mean of column y2, add the following code to the above snippet −

y1<-rpois(20,2)
y2<-rpois(20,5)
y3<-rpois(20,1)
y4<-rpois(20,5)
df2<-data.frame(y1,y2,y3,y4)
mean(df2$y2) If you execute all the above given snippets as a single program, it generates the following output −  4.05  To find the mean of column y3, add the following code to the above snippet − y1<-rpois(20,2) y2<-rpois(20,5) y3<-rpois(20,1) y4<-rpois(20,5) df2<-data.frame(y1,y2,y3,y4) mean(df2$y3)

If you execute all the above given snippets as a single program, it generates the following output −

 1


To find the mean of column y4, add the following code to the above snippet −

y1<-rpois(20,2)
y2<-rpois(20,5)
y3<-rpois(20,1)
y4<-rpois(20,5)
df2<-data.frame(y1,y2,y3,y4)
mean(df2$y4) If you execute all the above given snippets as a single program, it generates the following output −  4.9  ## Example 3 Following snippet creates a sample data frame − z1<-rexp(20) z2<-rexp(20) z3<-rexp(20) df3<-data.frame(z1,z2,z3) df3 The following dataframe is created −  z1 z2 z3 1 0.75901140 1.1019604 1.857275549 2 0.70534396 0.5027629 0.141321053 3 0.85023827 0.3935630 1.096067266 4 0.79056207 0.3866263 0.004878585 5 0.02140214 0.5251550 1.255923276 6 2.10659256 1.2074068 1.366982480 7 0.62689870 1.0928418 0.127860267 8 0.42471756 0.7221201 0.804941206 9 0.20822713 0.4138671 1.206996112 10 0.43427296 2.2273157 0.448053845 11 0.20142638 0.6122972 0.827769115 12 1.11057268 0.6116563 2.259519266 13 2.45655773 1.1361731 2.467388572 14 0.07043767 4.6228876 2.722874785 15 1.16999613 0.2022302 2.775020942 16 1.27551362 0.1391906 2.669347687 17 0.17801680 1.3281677 1.686527666 18 1.16893835 0.7579054 0.872252452 19 0.24239762 1.3178056 1.207718495 20 0.72186035 4.3268620 1.504209600 To find the mean of column z1, add the following code to the above snippet − z1<-rexp(20) z2<-rexp(20) z3<-rexp(20) df3<-data.frame(z1,z2,z3) mean(df3$z1)

If you execute all the above given snippets as a single program, it generates the following output −

 0.7761492


To find the mean of column z2, add the following code to the above snippet −

z1<-rexp(20)
z2<-rexp(20)
z3<-rexp(20)
df3<-data.frame(z1,z2,z3)
mean(df3$z2) If you execute all the above given snippets as a single program, it generates the following output −  1.18144  To find the mean of column z3, add the following code to the above snippet − z1<-rexp(20) z2<-rexp(20) z3<-rexp(20) df3<-data.frame(z1,z2,z3) mean(df3$z3)

If you execute all the above given snippets as a single program, it generates the following output −

 1.365146